There are an estimated 76 million illnesses, 325,000 hospitalizations, and 5,000 deaths per year due to food-related pathogens in the United States. Of these food related illnesses, approximately 62 million are due to undetermined pathogens. Considering this burden of disease, there is a critical need to improve our understanding of the causes of foodborne illnesses. Thus, this proposal is in response to a request for proposals from the National Center for Infectious Diseases. As a continuation of our previous work in exploring the causes of unexplained diarrhea through prior grants and through the Emerging Infections Program Sentinel Site Grant (aka: FoodNet), our goals for this work fall into three areas. First, we will continue to use the most sophisticated, currently available methodologies to define the causes of infectious diarrhea in patients seeking medical attention; second, we will determine the prevalence of antibiotic resistant enteric bacteria in the community; and third we will employ advanced molecular techniques to screen for novel pathogens. This research will allow us to increase our understanding of the causes of foodborne illnesses. Additionally, it has the potential for translation into public health practice in order to decrease the significant morbidity and mortality caused by these diseases. Considering the depth of expertise available at the University of Maryland, especially as it relates to enteric pathogens, we have an ideal environment to conduct these studies. Our three specific aims are: 1) Identify causes of diarrhea from known enteric pathogens in pediatric and adult populations presenting to the emergency departments and clinics within the University of Maryland Medical System, 2) Undertake antibiotic susceptibility determinations on selected enteric isolates from individuals with and without complaints of diarrhea, 3) Identify new pathogens by utilizing novel molecular methods (specifically denaturing gradient gel electrophoresis (DGGE), fluorescent in situ hybridization (FISH), and microarrays). The combination of sophisticated microbiologic techniques, antibiotic resistance determinations, and molecular methods provides an innovative approach to discovering the causes of gastroenteritis. Through this work, we expect to not only better define the causes of diarrheal illnesses in the Baltimore Metropolitan area, but to identify other pathogens that contribute to foodborne illnesses.